1. Field of the Invention
Embodiments of the present invention relate to a method for manufacturing integrated circuit devices. More particularly, embodiments of the invention relate to forming thin barrier layers using cyclic or atomic layer deposition.
2. Description of the Related Art
Copper has recently become a choice metal for filling sub-micron high aspect ratio interconnect features because copper and its alloys have lower resistivities than aluminum. However, copper and its alloys have a propensity to diffuse into surrounding materials such as silicon oxide, silicon, and other dielectric materials, for example, causing an increase in the contact resistance of the circuit. Copper and its alloys also have a propensity to diffuse into surrounding elements such as transistor gates, capacitor dielectrics, transistor wells, transistor channels, electrical barrier regions, interconnects, among other known elements of integrated circuits.
FIG. 1 is a cross-sectional view of a substrate 100 including an etch stop 112 over a copper interconnect 120 in a dielectric layer 110. A barrier layer 114 is deposited prior to the deposition of copper in the interconnect to prevent or impede the diffusion of copper atoms into the surrounding dielectric layer. However, copper may still diffuse into areas surrounding the interconnect, as conventional etch stop materials, such as SiN or SiCN, do not adhere well to copper. The weak connection between the etch stop and the interconnect can result in the diffusion of metal atoms into other areas of the substrate, causing cross-talk among the interconnects of the substrate and failure of the device formed by the substrate.
There is a need, therefore, for a method for depositing an adhesive layer on metal interconnects that prevents or minimizes the diffusion of metal atoms from the interconnect.